Involvement of maize Dof zinc finger proteins in tissue-specific and light-regulated gene expression.
Dof is a novel family of plant proteins that share a unique and highly conserved DNA binding domain with one C2-C2 zinc finger motif. Although multiple Dof proteins associated with diverse gene promoters have recently been identified in a variety of plants, their physiological functions and regulation remain elusive. In maize, Dof1 (MNB1a) is constitutively expressed in leaves, stems, and roots, whereas the closely related Dof2 is expressed mainly in stems and roots. Here, by using a maize leaf protoplast transient assay, we show that Dof1 is a transcriptional activator, whereas Dof2 can act as a transcriptional repressor. Thus, differential expression of Dof1 and Dof2 may permit leaf-specific gene expression. Interestingly, in vivo analyses showed that although DNA binding activity of Dof1 is regulated by light-dependent development, its transactivation activity and nuclear localization are not. Moreover, in vivo transcription and in vitro electrophoretic mobility shift assays revealed that Dof1 can interact specifically with the maize C4 phosphoenolpyruvate carboxylase gene promoter and enhance its promoter activity, which displays a light-regulated expression pattern matching Dof1 activity. We propose that the evolutionarily conserved Dof proteins can function as transcriptional activators or repressors of tissue-specific and light-regulated gene expression in plants.
Yanagisawa
S
S
Department of Life Sciences (Chemistry), Graduate School of Arts and Sciences, University of Tokyo, Japan. csyanag@komaba.ecc.u-tokyo.ac.jp
Sheen
J
J
D000595:Amino Acid Sequence; D002451:Cell Compartmentation; D002467:Cell Nucleus / Q000737:chemistry; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism*; D003624:Darkness; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins; D008027:Light; D008164:Luminescent Proteins / Q000235:genetics / Q000302:isolation & purification; D008957:Models, Genetic; D008969:Molecular Sequence Data; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000528:radiation effects; D010940:Plant Proteins / Q000378:metabolism*; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011523:Protoplasts; D011993:Recombinant Fusion Proteins / Q000302:isolation & purification; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D003313:Zea mays / Q000235:genetics* / Q000528:radiation effects; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D008164:Luminescent Proteins; C082345:MNB1A protein, Zea mays; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D014157:Transcription Factors; D049452:Green Fluorescent Proteins